gh-103053: Skip test_freeze_simple_script() on PGO build (#109591)

Skip test_freeze_simple_script() of test_tools.test_freeze if Python
is built with "./configure --enable-optimizations", which means with
Profile Guided Optimization (PGO): it just makes the test too slow.
The freeze tool is tested by many other CIs with other (faster)
compiler flags.

test.pythoninfo now gets also get_build_info() of
test.libregrtests.utils.